When the 5th Avenue dam was built on the Olentangy River in Columbus in 1935, it served a useful purpose – providing cooling water for a power plant on The Ohio State University campus. Many decades later, with the power plant long gone, the only thing the dam was accomplishing was damaging the health of the river. Dams often degrade rivers by destroying their natural flow patterns and creating lake-like conditions that trap pollutants and sediment and obstruct the migration of aquatic species. That’s exactly what was happening behind the 5th Avenue dam, which is why the City of Columbus retained Stantec to design its removal and restore 1.6 miles of the river to a more natural state.
As a result of a detailed feasibility study, we determined that for the western half of the 470-foot-long dam, only the top two feet of the structure needed to be removed. This saved significant time and money. Our natural channel design deepened the river and restored its natural flow and form, and four wetlands were created. More than 7,500 mussels of 13 distinct species were rescued and relocated in safer areas upstream and downstream of the restoration area. Seven new riffles now provide prime habitat.
Nearly all sediment removed from the river was reused to restore and expand the river’s banks, which were planted with native vegetation and other plants suited to riparian environments. The newly narrowed and vegetated banks offer a continually evolving green space that the university has already embraced as a center for research and recreation. Now canoers and kayakers can paddle through this newly restored stretch of the river without having to portage around the dam, and fishermen are returning to the area as its biodiversity rebounds.
Columbus Mayor Michael B. Coleman praised the site as “an environmentally-friendly corridor that preserves the health and vitality of the waterway for generations to come.”